Backing India's evidence on Mumbai [Images] attacks as 'totally credible', France [Images] on Saturday asked Pakistan to extend full cooperation to ensure that those behind the carnage are punished in the 'most severe way'.

At the same time, the influential European nation advocated that India and Pakistan should resume composite dialogue at an appropriate time as 'they have to live side by side'.

President Nicolas Sarkozy's diplomatic adviser Jean-David Levitte, who was in New Delhi [Images] to convey France's solidarity with India in the wake of the Mumbai attacks, evaded questions on whether his country believed official agencies of Pakistan were involved in the strikes.

Levitte, who met Prime Minister Manmohan Singh [Images] to convey Sarkozy's message and held talks with his counterpart National Security Adviser M K Narayanan to analyse the attacks, also evaded a reply when asked whether New Delhi's demand for extradition of the suspects was justified.

He said his country feels that the challenge posed by terrorism to India is a challenge to France and hence is 'available' to extend any kind of cooperation to New Delhi.

"The tragedy of Mumbai must be compared with 9/11. It was a challenge to a great democracy and values of a great democracy," Levitte told reporters after his meetings.

Citing Sarkozy's speech delivered to a gathering of French envoys in Paris on Friday, Levitte said, "It is necessary that Pakistan cooperates fully with India, the biggest democracy in the world, so that the terrorists responsible for Mumbai slaughter are arrested and punished."

Sarkozy said, "France wants to speak to Pakistan and France wants to be a friend of India."